The present invention pertains to a milling cutter that uses indexable inserts. More particularly, the present invention relates to a milling cutter with a cutter body with pockets that are capable of removably securing indexable inserts of various geometrical shapes.
Indexable cutting inserts are available in various shapes. One of the most common inserts is square and includes four cutting edges. Such an insert is especially useful in cases where it is necessary to mill a square or 90-degree shoulder in the workpiece being cut.
Octagonal inserts with eight cutting edges are also widely used. Adjacent cutting edges of such an insert extend at a 45-degree angle (commonly called a lead angle) relative to one another. Octagonal inserts are particularly advantageous in that a single insert possesses a relatively large number of alternately usable cutting edges.
Round inserts also are known. Such an insert may be infinitely indexed because the circular shape of the insert eliminates the requirement for indexing the insert through a particular angle. In addition to conventional round inserts, there are so-called hollow ground round inserts. The cutting face of a hollow ground insert is dished or relieved so as to produce an extremely sharp cutting edge on the insert.
Other inserts which are less widely used are irregularly shaped inserts having four cutting edges which are separated from one another by non-cutting edges. The cutting edges of a given insert may be located at a particular lead angle such as a 15-degree lead angle or a 30-degree lead angle.
Conventional tool holders are capable of indexing an insert with a particular cutting geometry. As a result, a different type of tool body is required to index a different type of insert. Such a practice of requiring a different type of tool body for a different type of insert is both expensive and impractical. Thus, it would be desirable to provide a tool holder capable of indexing inserts of various geometrical shapes.
An object of the invention is to provide a tool holder capable of indexing inserts of various geometrical shapes.
In one aspect of the invention, a milling cutter comprises a plurality of pockets positioned around an outer periphery of said cutter, an indexable cutting insert positioned within each of said pockets and means for securing each insert in its respective pocket. Each pocket includes a bottom, a first generally radially extending shoulder, and a second generally axially extending shoulder. Each insert includes a front face and a generally parallel rear face. The front face defines a polygonal cutting geometry and the rear face defining a substantially different seating geometry, such as a round seating geometry. A leading and circumferentially facing cutting face and a plurality of clearance faces extend between the front and rear faces. The cutting edges of each insert is defined as an intersection of one of the plurality of clearance faces with the cutting face. Each insert further includes a generally frustconical transition face extending between the clearance faces and the rear face for providing a transition area between the polygonal cutting geometry and the seating geometry of the insert. The securing means selectively permits indexing of each insert in its respective pocket to bring a selected one of the cutting edges into an active cutting position. The rear face of the insert is seated against the bottom of its respective pocket and two orthogonal clearance faces of the insert engage the shoulders of its respective pocket when the insert is positioned within its respective pocket.
In another aspect of the invention, a milling cutter comprises a plurality of pockets positioned around an outer periphery of said cutter, an indexable cutting insert positioned within each of said pockets and means for securing each insert in its respective pocket. Each pocket includes a bottom, a first generally radially extending shoulder, and a second generally axially extending shoulder. Each insert includes a front face and a generally parallel rear face. The front face defines a round cutting geometry and the rear face defining a substantially round seating geometry. A leading and circumferentially facing cutting face and a plurality of clearance faces extend between the front and rear faces. The cutting edges of each insert is defined as an intersection of one of the plurality of clearance faces with the cutting face. Each insert further includes a plurality of faceted faces and a generally frustconical transition face extending between the plurality of faceted faces and the rear face for providing a transition area between the faceted faces and the round seating geometry of the insert. The securing means selectively permits indexing of the insert in its respective pocket to bring a selected one of the cutting edges into an active cutting position. The rear face of the insert is seated against the bottom of its respective pocket and two orthogonal faceted faces of the insert engage the shoulders of its respective pocket when the insert is positioned within its respective pocket.